OA is one of the most common diseases of mankind, and nearly 50% of elderly individuals will suffer from either knee or hip OA in their lifetimes. OA commonly limits activity in the elderly. Significant functional disability is associated with hip OA in the elderly however very little information is available to influence the management of osteoarthritis in the population affected. We propose to study hip OA in the Mr. OS cohort study in which 6,013 older men from geographically and ethnically diverse populations were recruited 3 years before to characterize selected variables of probable importance of skeletal health. In this proposed ancillary study, we propose to utilize this large cohort of elderly men to evaluate the epidemiology of hip OA, including a genetic assessment. Hip OA is a common disease of elderly men. We hypothesize that there will be important demographic and lifestyle risk factors associated with hip OA in elderly men. Lastly with stored DMA already obtained from the Mr. OS cohort we will also examine the hypothesis that specific candidate genes of bone and cartilage metabolism are associated with an increased risk for hip OA in elderly men. To test our hypotheses we propose the following specific aims. 1. a. To determine the prevalence of radiographic osteoarthritis (OA) of the hip by obtaining a radiograph of the pelvis at the last visit of Mr. OS. 1b. To determine risk factors for hip OA in an elderly cohort of men. Specifically that age, weight, height, bone density, physical activity, neuromuscular impairment, prior hip injury, diabetes and OA in other joints, low serum free testosterone levels, low estradiol levels, type of occupation, are associated with prevalent hip OA. 2. To use our stored DMA samples to conduct a case-control study of the relationship of specific candidate genes and the risk of prevalent hip OA in elderly men. To accomplish these specific aims we propose to obtain a pelvic radiograph and perform a hip range of motion examination in all study subjects enrolled in the Mr. OS study when they are seen at final visit. All of the pelvic radiographs will be assessed for radiographic hip OA by a validated rating system and experienced radiograph readers. After determining the prevalence of hip OA in the Mr. OS cohort we will perform case-control studies of candidate genes associated with bone and cartilage metabolism.